1. Field of the Invention
The present invention relates to a flavoring granule for tobacco products, which encapsulates flavors to be added to tobacco products and is so designed to release said flavors encapsulated therein at a designed time.
The present invention also relates to a method for preparing said flavoring granules for tobacco products, each of which has a comparatively large diameter in a satisfactorily spherical shape in particular.
2. Description of the Related Art
Tobacco products, in general, are added by flavors for purposes of improving fragrant smoking taste. Most flavors to be added to said products are classified into two group: the primary flavor as a casing sauce and the secondary flavor as a top flavor. Both kinds of flavors are generally added directly to the shredded tobacco by means of spraying during the preparation process of tobacco products.
Among these flavors, especially many of the secondary flavors, however, are volatile so that they are readily volatilized to diffuse into an atmosphere and easily deteriorated due to a preparation heat or an air flow during the manufacturing process, which results in reduced efficiency of flavor-addition. Further, volatilization and deterioration of flavors can also occur during the product storage. On the other hand, when flavors are added in excess amounts from the view point of the flavor yield, it may cause troubles such as staines in the cigarette paper, etc.
Therefore, it has been proposed to utilize such secondary flavors in a form of flavoring granule wherein said flavors are encapsulated within a solid comprising natural polysaccharides or derivatives thereof, in order to protect the flavor from heat and air and to prevent volatilization and deterioration of the flavor (Unexamined Published Japanese Patent Application No. '89-27461). Such flavoring granule was contained in a filter tip of a cigarette and was crushed or broken by being pressed with fingers of a smoker at the time of smoking, rendering the flavor sealed therein to volatilize and diffuse.
To prepare such flavoring granules, there has been disclosed a method as below (Unexamined Published Japanese Patent Application No. '89-27461).
First, flavor substances to be encapsulated in granules are mixed with an aqueous solution of natural polysaccharides or derivatives thereof, such as sodium alginate and carageenan, etc. The resultant flavor mixture is allowed to drop, as illustrated in FIG. 1, from the tip of a nozzle 1 as a drop 2 into a hardening solution 3. The natural polysaccharides contained in the drop 2 are gelated by the hardening solution 3 to form a granule 4 which is encapsulating said flavor. As the hardening solution, aqueous solutions of metal salts such as salts of calcium, potassium, magnesium, and aluminum, etc. can be used.
In the above method, the diameter of the granule 4 has been controlled by adjusting the concentration (i.e. viscosity) of said aqueous solution of polysaccharides or an outer diameter of the nozzle 1. When a concentration of the solution is constant, the diameter of the granule 4 is directly proportional to the outer diameter of the nozzle 1 in a certain range. When the outer diameter of said nozzle 1 is constant, the higher the concentration is the larger becomes the diameter of said granule 4. However, the control effect of the granule diameter obtained by the concentration adjustment is not so prominent as compared with that obtained by the nozzle adjustment.
The above mentioned flavoring granules according to said prior art have been confronting with such drawbacks as: too hard to be crushed because of their small size in diameter and their high density. In addition, they seldom break into fine pieces when crushed, so that the flavoring effect can not be attained sufficiently. Furthermore, since a change of touch upon crushing can not be felt clearly, it is difficult to confirm whether the granule in the filter tip is broken or not.
Hereinbelow, problems concerning the granule diameter will be explained in detail.
The largest diameter of the granule 4 in accordance with said prior art is, at the most, 7 mm in a condition before drying and about 4.5 mm after drying. Even when the outer diameter of the nozzle 1 is extremely enlarged, a drop having a larger diameter than above can not produced. If the concentration of the raw liquid for granules is increased so as to elevate the surface tension of the drop 2, the granule 4 will have, though a little larger diameter, not a spherical shape but an indefinite shape such as oval, rod and the like. The reason why the spherical shape can not be obtained is that the drop has too high viscosity to become spherical spontaneously in the air, and it falls into the hardening solution 3 with the indefinite shape and hardens therein as it is.
Further, as illustrated in FIG. 2, even when the raw solution is extruded from the tip of the nozzles immersed into the hardening solution 3, the drop 2 will harden in a rod shape before it gets spherical.